METROPOSTCARD.COM GUIDE TO PRINTING TECHNIQUES 7
> Techniques   Home   History   Glossary   Guides   Publishers   Artists   Topicals   Warfare   Blog   Contact


Facsimiles & Identification


graphic





SIMILARITIES OF TECHNIQUE


Every printing technique has its own individual characteristics, which should make them easy to identify. The problem is they all come with variances that make it impossible to identify a set look. When this is coupled with characteristics shared between mediums, simple knowledge won’t due when trying to decipher them. Some of this confusion is just in the nature of the medium, while at other times it is the result of printers trying to keep trade secrets hidden. It can take very close scrutiny to determine a technique but even this does not always yield results. Even so, a broad knowledge of printing goes a long way when one must extrapolate limited information. All the examples below will give some clues into the most mysterious techniques found on postcards, but there aren’t always answers to all questions.



PROBLEMS IDENTIFYING COLLOTYPE

The printing plates used with photogravure and collotype both hold ink in the spaces formed between particles of resist that leave their own distinctive patterns on the final print. They show up as white dots on photogravure from where the grains of aquatint once sat on the plate to prevent biting in the acid bath. The small white marks on collotypes tend to be wormy in appearance as they are the result of the light hardened reticulated gelatin emulsion. A further distinction between these two processes is in their tonal structure. On close examination the ink in photogravure sits as a crust atop a paper’s surface creating rich flat blacks while the thiner ink film of a collotype produces a good range of grey but poor dark tones. While these are the major differences to look for in making a determination of technique there is a problem, they are based on an average look that does not always hold true.

Many different patterns can be created with aquatint. If the rosin crystals are heated too long or over too high a heat they can melt into each other creating chain-like patterns that are similar to curdled gelatin. The grain found in collotype is very dependent on the drying process of plates, which often took place in special drying boxes. If the gelatin emulsion is very absorbent, it will produce a small tight grain that are sometimes so small they have no distinctive shape at all and cannot be differentiated from a fine aquatint. If the gelatin emulsion is too thick, a coarse grain will result that resembles fused aquatint particles. The amount of organic material in the emulsion can further change the size and shape of reticulated curdles. Various practitioners of collotype had many trade secrets that often rendered the textures produced by one shop different from another.

Illustration

Collotype Press: Note that this 19th century collotype press has two sets of rollers for two separate inking slabs on the left. The plate would slide under one set and be rolled with a stiff ink, then slide under the other set and be rolled with a thiner ink. This method produced richer blacks than were attainable with a single pass under a roller.

Some printers also managed to push the collotype process into producing real blacks. While these prints do not generally display the dark crust found in photogravure, they can often come close enough to cause confusion. Collotypes were typically printed with one inking but some printers inked their plates twice. Here a stiff ink that only adhered to the most light exposed areas was used first to create the dark shadows. It is then followed by a thinner ink discharged from a composition roller used for the medium or light tones. The second rolling tends to pick up ink from the light areas of the first roll making them brighter while deepening the darks already inked. Collotypes were also darkened by double printing them. The plate would be inked then printed, then re-inked and printed again on the same sheet of paper during the same press run. While all this may have created a more appealing image, it removes paleness from the list of typical characteristics to look for when identifying technique.

Postcard

Photogravure and Collotype: The postcard above was printed in photogravure by the National Art Views Company in 1904. After the Rotograph Company bought all their negatives they published their own version of the same image seen below just a couple years later but as a collotype. The grain on both cards is so small that they are almost indistinguishable from each other.

Postcard


Postcard Detail

Photogravure and Collotype: Even though fine textures can be achieved through photogravure, this medium forms a heavy crust wherever marks fuse together to form black as seen in the detail above. While collotypes are known for their light texture they too can form a similar looking crust under certain conditions like double printing. In the detail below we can see the same tight patterns forming only on a larger scale. Within them however a smaller reticulated pattern is visible. Such clues are not always easy to find as they are often dependent on printed nuances used to render a composition.

Postcard Detail


The large amount of variances in the collotype process can cause many problems in identification. Printing houses making collotypes were particularly secretive about the specific details of their processes. Collotypes were introduced to the public under various brand names, which may or may not have been distinguishable from each other. Since all names for collotype eventually became interchangeable, matching a nuanced technique to a name is now meaningless as no real distinctions can be made. Today no one can be quite sure to what any trade name refers to. Heliotypes are supposedly printed by double rolling two different inks onto a single plate, but many with this name have been printed from the pass of one roller like an ordinary collotype. Some refer to all collotypes printed in Europe as heliotypes regardless of the way they look or were made. On top of this many have the same crusty surface in their darkest areas as found on photogravures. When the grain has no discernible characteristics or disappears completely into blackness, it becomes difficult if not impossible to make a determination regarding technique.


Postcard

Heliotype or Collotype: The reticulated texture on both of these postcards is just about the same but the darkest tonalities on the image above have a washed out look while nearly all the details in the image below are a crusty looking black. Though the image above is definitely a collotype, should the image below be considered a variation of what can be achieved through the collotype process or is it a distinctly different heliotype? While the physical differences are easy to decipher, the problem in identification may lay in that there may never have been a clear definition assigned to either.

Postcard


Postcard Detail

Heliotype or Collotype: The blacks on this postcard are dark, crusty, and nearly solid. The occasional white fleck within them makes this texture reminiscent of photogravure. In the light areas however, a more reticulated texture is more easily visible. The question that then remains, is this an extraordinary collotype or should it be considered a heliotype? Perhaps it was just double printed? It also demonstrates how easy it is to confuse with gravure when there are no light values available from which texture can be examined.


Postcard

Halftone or Heliotype: At first glance the early view of London above seems to capture all the detail and rich shading normally found in many of the collotypes of the period. Under magnification it is obviously but surprisingly printed through a line block halftone. Below is a similar scene printed as an actual collotype. While the details in the collotype are much finer, they both rely on the mindís ability to extrapolate on the information the eye receives, and they both nearly provide the same clues to read the image in a similar manner.

Postcard


Postcard

Photogravure or Heliotype: This postcard reproduction of a drawing is made up of many irregular blots, which closely resemble the feel of a drawn line block. A closer view however reveals that the blots are dark, heavy, and crusty, like you would find in photogravure or Heliotype, and not at all consistent with the thiner ink used in line block. There is little texture to examine when searching for further clues because the light values tend to be little more than faint points, and the darks fade into a solid mass. There is one small patch of a more medium tone at the feet of the skaters, seen below, where a reticulated texture can be found, revealing the card to be a heliotype.

Postcard Detail


Postcard Detail

Rotogravure: Rotogravures are made from such a distinct printing process that their grid like pattern should be easily discernible but this is not always true. Not only does this pattern completely disappear in the darker values, their spacing in middle tones create irregular white dots as seen in this detail that can be mistaken for the aquatint pattern of photogravure or the barnacle like pattern sometimes created by collotype.


Postcard

Tinted Photogravure: Lithography was used to print the red, yellow, and blue tints as spatter in the postcard. The key plate is printed with such high contrast that little grey is produced and it becomes very to find any texture as seen in the detail below. While it has all the characteristics of having been made through photogravure, the possibility that it is a tinted rotogravure or even collotype cannot be completely ruled out.

Postcard Detail


Postcard Detail

Tinted Collotypes: Both of these details from two different tinted collotypes have been enlarged by the same scale. While the one above reveals the typical reticulated wormy texture of a collotype, the one below is closer to what might be expected from photogravure. It is this type of variance that tends to cause the most problems in identification.

Postcard Detail

When collotype and photogravure are printed in multiple colors they may become almost impossible to distinguish from one another. Looking for slight nuances in printing grain may be of no help when many fine marks from different plates overlap into a jumble. Many of the printers who used these techniques often employed uncoated papers, which means that the paper’s fibers can be more obtrusive than the ink when magnified, breaking up any perceivable printing patterns even further. Terminology is also of no help as the collotype process was often referred to as photo engraving, which also describes the gravure process.

While photogravure was used to make postcards, it is really not that common. The gravure process was largely employed through rotogravure, which is much easier to identify because of its rigid ink well grid. Collotype was even more widely used to create postcards. While these numbers alone cannot lead to a positive identification of technique, they do point in the direction to where clues should be most sought.

Postcard

Color Collotype: The matte finish on this card is very reminiscent of gravure but its surface lacks the typical signs of patterning found in rotogravure. The detail below shows that even close up the printing grain is almost indistinguishable. While it is still close to photogravure in appearance, some reticulated grain becomes visible in the extreme enlargement further below. This tell tale grain is not always apparent when collotype plates are overlapped in color printing.

Postcard Detail

Postcard Detail


Postcard

Color Collotype: Four plates holding red, yellow, blue, and black ink were used to make this postcard dating from 1953. The grain on this card is so tight that the technique is almost undeterminable. Even the red on the roof in the detail below looks like smeared hand coloring but this color is off register in the same manner throughout the image indicating it is a printed reproduction of a painted smear.


Postcard

Collotype vs Lithography: The textures created by collotype and lithography are normally easy to differentiate from one another when magnified, but to the naked eye they can look very much alike. Both techniques produce continuous tonalities and as we can see from these two postcards they also produce the same look when their style is similar. The tinted collotype above shares a similar tonal range and palette with the chromolithograph below.

Postcard


Postcard Detail

Collotype vs Lithography: From these two details of the postcards further above we can better see how different their textures are despite their similar overall appearance. The picture below clearly reveals the hand drawn dots of chromolithography while the photomechanical collotype above remains grainy even when enlarged at the same scale.

Postcard Detail


Postcard

Heliotype vs Lithography: If collotype can be difficult to differentiate from lithography, this problem can be compounded when they both try to imitate the same stylistic conventions. Both of these early cards depict the same castle in snow, but the card above is a heliotype and the one below is a tinted lithograph in black and grey.

Postcard

Around 1885 Sprague & Company developed a method they termed Ink-Photo that allowed for the transfer of a collotype to a litho-stone by the means of transfer paper. Since it was difficult to match up the fine grain normally found in a collotype with the fine grain of a litho-stone, a thicker gelatin emulsion was used to produce a coarser reticulated surface. The final prints still maintain a random series of markings, but by enlarging their scale the image lost the delicacy of tone normally associated with collotype. This very distinct grain should make them easy to identify except this transfer process was also used to create transparencies for random mezzograph screens used in photomechanical printing. A collotype plate could be exposed to a negative and then the processed image transferred to a litho-stone or a photosensitized stone could be exposed to the same negative made to create the collotype through a mezzograph screen. Since the image comes from the same source and both techniques have an ink-photo texture, the final prints are identical except for the randomness of the pattern. Ink-photos were a short lived process with few being made beyond the turn of the century. Most postcards with this texture were therefore probably made photomechanically with a mezzograph screen, but there were so many little printshops producing postcards at the beginning of the 20th century that it becomes impossible to definitively say what technique was employed.

Postcard

Ink-Photo or Mezzograph: This unusual English postcard from the 1930ís has a large reticulated texture but it is impossible to say with certainty how it was made. Most postcards produced with this texture after 1900 are most likely made photomechanically with a mezzograph screen.





Back  UP  Next

Return to Menu



graphic